BOUNDARY OF THE GLACIATED AREA. 147 



the Catskills — we find still the same characteristic deposits 

 slightly modified by the different conditions. A range of 

 hills, sweeping aronnd this plateau for ten or twelve miles in 

 a magnificent semicircle open toward the south, was discov- 

 ered, in 1881, by Professor Lewis and myself to belong to the 

 extreme and true terminal moraine of the continental ice- 

 sheet. South of it one may go for miles upon a level, sandy 

 plateau (about two thousand feet above tide) without en- 

 countering a bowlder or any foreign material ; while the low 

 range of hills, seventy -five or a hundred feet in height, is 



Fui. 4S. — The previous pebble viewed from the edge. The reversed side was free from 



clari.-il marks 



glacial marks 



literally formed of bowlders ; among which may readily be 

 recognized those of granitic origin, wrenched from ledges 

 hundreds of miles to the north, and transported hither across 

 the valley of the Mohawk or over the broad expanse of Lake 



